How Does a Submarine Go up and down?

A submarine is different from other ships, though, because it can control its buoyancy. This means the submarine captain can decide when to sink down into the ocean or come back up to the surface.

In order to control buoyancy, the submarine relies on special tanks called, ballast tanks, which can be filled with water or air, built into submarines. The tanks are filled with air when the submarine is floating on the surface of the water. The air keeps the submarine buoyant, just like any other kind of ship.

To submerge, water is let into the ballast tanks to greatly reduce the vessel’s buoyancy. The sub is then hydro-planed (glided) beneath the surface by the thrust of its propellers, and the downward angle of its bow and tail fins. To surface, the sub is steered upward, and the water is forced out of the ballast tanks with compressed air. This process is called “blowing” the tanks.

Living on a submarine might sound like fun, but there are challenges to life under the sea. The three biggest problems involve maintaining air quality, fresh water supply, and temperature.